Cacti of Southwest USA

Cacti are found in virtually every US state and the southern Canadian provinces, mostly just a few hardy species of opuntia and escobaria, but they are much more widespread in the desert regions of the southwest. There are six states where cacti are abundant, namely (with the approximate number of US species): Arizona (83), California (35), New Mexico (56), Nevada (26), Utah (34) and Texas (91).

The densest colonies are generally found at the lower elevations and most southerly locations, corresponding to the Sonoran, Chihuahuan and Mojave deserts. Of these three, the Mojave has rather fewer species, owing to its low rainfall, and the hottest part of the Sonoran Desert in southeast California and southwest Arizona also has a relatively small number for the same reason: the best places of all to see cacti are south and southeast Arizona, south New Mexico, and far west Texas, especially in the Big Bend region.

Cacti of Utah are distributed across most of the state - not just in the low elevation regions of the southwest (at the edge of the Mojave Desert), but all across the Colorado Plateau and around the Uinta Basin of the northeast. There is no single best location, but the famous national parks (Arches, Capital Reef, Zion, Canyonlands) are each home to over a dozen species, and Utah has around six types of cactus not found anywhere else in the US (sclerocactus and pediocactus species).